Structural and electronic characterization of Co nanostructures on Au(332)

Abstract

Co nanoislands were grown on (332) vicinal surface of Au in UHV using the e-beam evaporation technique. Scanning tunneling microscopy results reveal that Co deposition occurs following an islanding mode for θCo ranging from 0.17 to 0.64 ML. At low coverage nanoislands show a monolayer height, while at higher Co loadings, islands have a maximum bilayer height. XPS measurements rule out the possibility of alloy formation provided that binding energy of Co2p core lines remains unchanged as cobalt loading increases. Also, XPS data reveals that, when subjected to thermal annealing, Co atoms diffuse into Au crystal retaining its chemical nature as before the annealing. Finally, NO adsorption experiments show that Co nanostructures are partially oxidized upon adsorption, as evidenced by changes in core photoemission lineshapes of the Co2p lines. Also, NO adsorption seems to inhibit Co atom diffusion into Au crystal during moderate thermal treatment.